Soybean Cyst Nematode: The Neglected Threat In U.S. Fields

SCN populations’ adaptation to genetic resistance a cause of concern for experts

Education, alternate SCN management options needed for growers

At a recent seminar, Syngenta shared results from a survey revealing that a significant number of growers do not consider soybean cyst nematode (SCN) to be a serious threat. Despite this underestimation, SCN is one of the most damaging soybean pests, costing growers an estimated 128 billion bushels of soybeans every year. SCN is found in every soybean-producing state across the U.S., and once present in a field, it cannot be eliminated.

Syngenta sponsored the SCN Awareness and Education Meeting in December 2015 as part of its dedication to providing soybean growers with effective solutions to combat this prolific pest. A broad group of university nematologists, university researchers and representatives from the soybean community discussed the current state of SCN in the U.S., the level of grower awareness and the ongoing research into evolving management strategies. A focal point of the discussion was a fall 2015 survey of more than 1,000 U.S. soybean growers from 17 states.

“The survey provides a baseline assessment of growers’ awareness of SCN, its perceived impact and the SCN management strategies used today,” said Wouter Berkhout, soybean Seedcare product lead at Syngenta.

The survey also revealed that while most growers plant SCN-resistant varieties as a management strategy, a majority of respondents don’t think SCN-resistant varieties have been losing efficacy. However, research has revealed that SCN populations are adapting to genetic resistance.

For more than 20 years, genetic resistance in varieties has come almost exclusively from a single source (PI88788), which is now found in more than 95 percent of SCN-resistant soybean varieties. As with weed resistance, reliance on a single management tool has reduced effectiveness. Research shows that SCN populations have adapted to PI88788, increasing the need for alternate solutions.

“Nematodes adapt to varieties faster than they adapt to sources of resistance,” said Terry Niblack, professor and chair, nematology, at The Ohio State University. “Against a variety, SCN is going to adapt much faster, and the likelihood of yield loss is much higher.”

With scientific evidence of adaptation and the level of growers’ awareness and management practices reflected in this survey, experts agree there is a clear need for additional studies and education.

“The findings confirm that we, in the soybean community, need to work as a team to combat the growing problem of SCN,” said Palle Pederson, Seedcare product marketing head at Syngenta. “This is not something that we can do by ourselves. Growers need to be better informed about issues affecting their soybean fields, and we need to provide more tools to counteract those issues.”